Internal combustion engines are coupled to engine boosting systems which deliver boost to the engine to meet engine torque demands. The engine boosting system may include a compressor delivering compressed air on an inlet side of the engine, increasing the boost available to the engine. Addition of an oxygen enhancer into cylinders of the internal combustion engine lowers inlet air temperature, elevates cylinder pressure, and provides boost to the engine by allowing the engine to burn more fuel. Increased fuel combustion creates more cylinder pressure driving down the pistons, turning the crank train with greater force which results in more engine power to meet torque demands. One widely used oxygen enhancer is nitrous oxide. When Nitrous oxide (N2O) is injected into the engine cylinders, the initial combustion within the cylinder creates enough heat to separate the nitrous oxide into its two components, nitrogen, and oxygen. Once this separation occurs, the oxygen can then be used to burn more fuel in the engine.
Attempts to deliver boost to the engine include the system disclosed by U.S. Patent Application No. 20110308483 A1, which discloses a nitrous oxide injection system, where the nitrous oxide is stored under high pressure in a tank and is directed from the tank to a fuel supply line. The nitrous oxide mixed with fuel in the fuel supply line is directly delivered into the engine cylinders to provide the requested boost to the engine.
However, the inventor herein has recognized an issue with the above approach. While some vehicle conditions require a high, sustained boost demand (e.g., engine boosting systems in race cars) most real world driving conditions require relatively short durations of boost for providing additional power to the engine (e.g., during acceleration events). As such, some engine boosting systems may be built to provide more boost than is actually needed, increasing vehicle system cost and complexity.
The inventor herein proposes a two-step boosting system to address the above cited problems, at least partially. In one example, the two-step boosting system may include a nitrous oxide storage tank fluidically coupled to an engine through a feed line, an air pump driven by a transmission of the engine, the air pump fluidically connected to a frame rail boosting system fluidically coupled to the engine, a first valve regulating nitrous oxide flow from the feed line to the engine, and a second valve regulating air flow from the frame rail boosting system to the engine.
An example method of operating a two-step boosting system may include, responsive to an engine torque demand above a threshold, injecting nitrous oxide from a nitrous oxide injection system to an engine, and responsive to the engine torque demand above the threshold for more than a threshold time and responsive to a pressure of a frame rail boosting system above a threshold pressure, suspending nitrous oxide injection and injecting compressed air to the engine from the frame rail boosting system, the frame rail boosting system receiving compressed air from an air pump driven by a transmission of the engine.
In this way, boost may be supplied to the engine either by nitrous oxide injection or by switching to injecting compressed air stored in the frame rail boosting system, providing a cost effective and efficient system for delivering boost during real world driving conditions.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.